摘要
裂隙的粗糙度对单裂隙中的溶质运移有着重要的影响,然而粗糙元的形状(粗糙裂隙壁面上的各种凸起/坑洼)对单裂隙中溶质运移的影响机理尚未完全清楚。该研究通过求解纳维—斯托克斯方程和溶质运移方程模拟了具有不同粗糙元形状(矩形、梯形、三角形)的单裂隙中的溶质运移,并利用稀释指数量化了裂隙内溶质的空间分布。模拟结果表明粗糙元起始处的切线方向与流线的夹角越大,则发育的涡流体积越大,引起的溶质非均匀流动越明显;对溶质运移突破曲线和停留时间分布的分析表明随着流速的增加,溶质运移逐渐由费克运移转变为非费克运移,其相应的突破曲线表现出越来越显著的"早到"和"拖尾"特征;粗糙元密度与停留时间分布的幂律拟合参数b之间存在明显的正相关关系;对于相同的雷诺数,矩形粗糙元引起的非费克行为比梯形和三角形粗糙元更显著。该研究有助于进一步完善粗糙裂隙溶质运移理论。
The roughness of fracture has an important effect on solute transport in a single fracture.However,the influence mechanism of roughness element shapes on the solute transport in a single fracture is not fully explored.In this study,the solute transport in a single fracture with different roughness element shapes(rectangle,trapezoid and triangle)by solving the Navier-Stokes equation and the solute transport equation is simulated,and spatial distribution of solute in the fracture is quantified by the dilution index.The simulated results show that the larger angle between the tangent direction at the beginning of the roughness elements and the streamline leads to the larger eddy near it,and further causes more non-uniform flow.The analysis of the solute transport penetration curve and residence time distribution(RTD)shows that with the increase of flow velocity,the solute transport changes gradually from Fickian law to non-Fickian one,and the"early arriving"and"tailing"of corresponding breakthrough curves are more and more significant.The power-law fitting parameter of residence time distribution is positive correlated with the density of rough elements.At the same Reynolds number,the non-Fickian behavior caused by rectangular roughness elements is more significant than that caused by trapezoi dal and triangular roughness elements.This research helps to further understand the mechanism of solute transport in rough fractur es.
作者
高峰钧
马雷
马海春
邓亚平
钱家忠
GAO Feng-jun;MA Lei;MA Hai-chun;DENG Ya-ping;QIAN Jia-zhong(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
2021年第4期516-522,共7页
Chinese Journal of Hydrodynamics
基金
国家自然科学基金(41831289,41772250,42072276)。
关键词
单裂隙
溶质运移
粗糙元形状
雷诺数
非费克
Single fracture
Solute transport
Roughness elements
Reynolds number
Non-Fickian
